The use of a syringe pump for infusion of medicament is well known. In a syringe pump, an activating force causes the movement of a plunger to expel fluid from the pump's chamber. Typically, an electric motor provides the activating force. For example, U.S. Pat. No. 4,585,439 discloses a portable infusion unit driven by a motor. The unit is configured so that once all the medicament has been used from an injection ampule, another injection ampule can be inserted in the unit. The motor increases the weight and size of the unit. Smaller motors are available. However, irrespective of size, the inclusion of a motor increases manufacturing costs and makes the design of a disposable, single-use unit unrealistic.
There are other disadvantages to reusable syringe pumps. The batteries powering the electric motor need to be either replaced or recharged. Even if a motor is not used to drive the plunger, the maintenance associated with a reusable device can be troublesome.
Thus, there exists a need for an improved apparatus for delivery of a fluid.